Human synovial sarcoma (SS) is a soft tissue sarcoma that is associated with a translocation event, t(X;18)(p11.2;q11.2), which fuses the SS18 gene on chromosome 18 to one of three closely related genes—SSX1, SSX2, or SSX4—on the X chromosome, resulting in an in-frame fusion protein in which the eight C-terminal amino acids of SS18 are replaced with 78 amino acids from the SSX C-terminus. This type of sarcoma accounts for about 8-10% of all soft-tissue malignancies and commonly occurs in the extremities of young adults and pediatric patients at inaccessible locations, which are often discovered late in the course of the disease. These malignancies are generally refractory to conventional chemotherapy-based forms of treatment; except for a small percentage of cases in which the tumors can be successfully removed with surgery, they are nearly always lethal. This underscores a significant need for novel therapeutic approaches in this disease. The present invention addresses these issues.